Add side panels, task selection, graph animation, and project docs

- Foldable left panel (user profile) and right panel (task details)
- Clicking a task in the list or graph node selects it and shows details
- Both views (task list + graph) always mounted via absolute inset-0 for
  correct canvas dimensions; tabs toggle visibility with opacity
- Graph node selection animation: other nodes repel outward (charge -600),
  then selected node smoothly slides to center (500ms cubic ease-out),
  then charge restores to -120 and graph stabilizes
- Graph re-fits on tab switch and panel resize via ResizeObserver
- Fix UUID string IDs throughout (backend returns UUIDs, not integers)
- Add TaskDetailPanel, UserPanel components
- Add CLAUDE.md project documentation

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/node_modules/handlebars/lib/handlebars/helpers/block-helper-missing.js

@@ -0,0 +1,35 @@
+import { appendContextPath, createFrame, isArray } from '../utils';
+
+export default function(instance) {
+  instance.registerHelper('blockHelperMissing', function(context, options) {
+    let inverse = options.inverse,
+      fn = options.fn;
+
+    if (context === true) {
+      return fn(this);
+    } else if (context === false || context == null) {
+      return inverse(this);
+    } else if (isArray(context)) {
+      if (context.length > 0) {
+        if (options.ids) {
+          options.ids = [options.name];
+        }
+
+        return instance.helpers.each(context, options);
+      } else {
+        return inverse(this);
+      }
+    } else {
+      if (options.data && options.ids) {
+        let data = createFrame(options.data);
+        data.contextPath = appendContextPath(
+          options.data.contextPath,
+          options.name
+        );
+        options = { data: data };
+      }
+
+      return fn(context, options);
+    }
+  });
+}